Recently polyamide resin as an engineering plastic has been used as a material for parts of light emitting diodes (LEDs). Because LEDs have good energy efficiency and long life, LEDs can replace conventional light sources, and interest in LEDs has been rising. Polyamide resin can be used in LED parts such as reflectors, reflector cups, scramblers, housings, and the like. The polyamide resin can be a high heat resistant modified polyamide resin which is reinforced with glass fiber and comprises an aromatic ring as a part of its main chain.
However, in order to be used as a material for LED parts, the polyamide should resist heat generated during the manufacture of LEDs and have a high initial whiteness index and excellent reflectance. Simultaneously, consistent irradiation of the LED by light sources can cause yellowing, which reduces the whiteness index. Thus, deterioration of whiteness should be minimized. Also, the resin can block the flow of electricity.
LEDs generally include a semiconductor emitting a light, a lead wire, a reflector as a housing, and a transparent sealing product sealing the semiconductor parts. The reflector can be made of ceramic or heat resistance plastic. Ceramics, however, have problems with productivity. Also, in the case of heat resistance plastics, injection molding can heat harden the sealing material, and also optical reflectance can decrease due to changes in color that can occur in the environment in which the LED is used.
Korean Patent Publication No. 2007-7026437 discloses a polyamide resin composition stated to have excellent surface reflectance and heat resistance, which is prepared using inorganic fillers and white pigments. However, when the polyamide resin composition exposed to high temperature and high humidity, over time color can change and reflectance can deteriorate.
Accordingly, there is a need for a material to replace traditional ceramic or heat resistance plastics used in the production of LED parts, such as reflectors.